Convertible crutch

ABSTRACT

An improved crutch quickly and conveniently convertible for use on normally dry or on slippery surfaces wherein a retractable prong or spike is incorporated in the base of the crutch; the spike being lowered or withdrawn by means of a hand operated mechanism located at or immediately below the hand grip of the crutch.

United States Patent [191 Pfaff [451 May 6,1975

[ CONVERTIBLE CRUTCH [76] Inventor: Carl F. Pfaff, P.O. Box 155, CaveCreek, Ariz. 85331 [22] Filed: June 3, 1974 [21] Appl. No.: 475,629

[52] US. Cl 135/53; 135/59 [51] Int. Cl A61h 3/02; A45b 9/04 [58] Fieldof Search 135/53, 55, 50, 59

[56] References Cited UNITED STATES PATENTS 5/1889 Remillard 135/538/1907 Dunkel 3/1948 Clemens 135/53 2,665,701 6/1954 Thackeray 135/533,448,749 6/1969 Stark ..135/53 Primary Examiner-Richard J. Scanlan, Jr.Assistant ExaminerC0nrad L. Berman Attorney, Agent, or Firm-Warren F. B.Lindsley [57] ABSTRACT An improved crutch quickly and convenientlyconvertible for use on normally dry or on slippery surfaces wherein aretractable prong or spike is incorporated in the base of the crutch;the spike being lowered or withdrawn by means of a hand operatedmechanism located at or immediately below the hand grip of the crutch.

1 Claim, 9 Drawing Figures PATENTEBHAY 61975 '5 SHEEI 10F 2 CONVERTIBLECRUTCH BACKGROUND OF THE INVENTION Many who have had to walk with theaid of a pair of crutches have undoubtedly experienced the difficultyand danger involved in trying to find a reliable footing for the base ofa crutch on slippery or icy sidewalks or pavements. The ordinary crutchis almost useless in such a situation and the hazard of adding furtherinjury to the initial infirmity is always a posibility.

The development of a fixed tread for the base of a crutch which willserve equally well for normal and for icy surfaces must rely on acompromise between a spike which is ideal for an icy surface but tooharsh and abrasive for normal surfaces and a rubber tread which is idealfor normal surfaces but lacks the ability to grip an icy surface.

An alternate is a special crutch which is easily and quickly convertiblefrom an ideal crutch for ice to an ideal crutch for normal surfaces.

An improved crutch of this type is urgently needed as a humanitarian aidto a significant segment of our population which has already sufferedmisfortune and can ill afford further injury.

SUMMARY OF THE INVENTION In accordance with the invention claimed, animproved crutch is provided which incorporates a retractable spike orprong which is useful for walking on icy surfaces It is, therefore, oneobject of this invention to provide a crutch which is ideally suited foruse on icy surfaces.

Another object of this invention is to provide such a crutch with ameans for retracting the prong or spike thereby converting the crutchinto an ideal appliance for use on normal surfaces.

A further object of this invention is to provide such a crutch whereinthe retracting means may be easily and quickly operated by the userwhile standing or pausing between slippery and normal surfaces.

A still further object of this invention is to provide such a crutchwhich is light in weight, easy to handle, and is of substantially thesame size as an ordinary crutch.

A still further object of this invention is to provide such a crutch ina simple and inexpensive design which is at the same time durable andattractive.

Further objects and advantages of the invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize this invention will be pointed out with particularity inthe claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be morereadily described by reference to the accompanying drawing in which:

FIG. I is a perspective view of a convertible crutch embodying theinvention.

FIG. 2 is a partial cross-sectional view of the crutch shown in FIG. 1taken along line 2-2.

FIG. 3 is a cross-sectional view of the rubber tread of the crutch shownin FIG. 1 taken along line 3--3.

FIG. 4 is an enlarged partial-side view of the retracting mechanism ofthe crutch shown in FIG. 1 with the mechanism shifted to a differentstate.

FIG. 5 is an exploded assembly view of the retracting mechanism employedin the crutch shown in FIGS. l-4.

FIG. 6 is an illustration of an alternate means for retracting the spikeshowing a second embodiment of the invention.

FIG. 7 is a further illustration of the retracting mechanism shown inFIG. 6 in a different state.

FIG. 8 is an enlarged partial side view of the retracting means shown inFIGS. 6 and 7 taken along the line 88 of FIG. 7.

FIG. 9 is an exploded assembly view of the retracting mechanism shown inFIGS. 6, 7 and 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawing by characters of reference, FIGS. 15 disclose a crutch 10comprising a pair of spaced elongated support members l1 and 12interconnected at one end by a padded cross member 13 which fits underthe armpits of the user, a handgrip 14 arranged laterally between andattached to the support member 11 and 12 at a point between their ends,and a tread member 15 interconnecting support members 11 and 12 at thebase of the crutch. In accordance with the invention claimed a pointedspike 16 is arranged to pass through an opening 17 in tread member 15and ia secured to a rod 18 arranged to extend between support members 11and 12 in substantially the same plane. A retractor support member 19,retractor mechanism 20, and a coupler 21 interconnecting rod 18 to theretractor mechanism 20 is provided for controlling the position of thespike. Spike 16 may be the pointed end of rod 18 or a separate membersecured or threaded thereto.

The retractor mechanism 20 comprises a flat rectangular plate or block22 supporting a staple or u-shaped bar 23 within a pair of apertureslater discussed. Block 22 is pivotally mounted by means of a centrallylocated pivot pin 24, a compression spring 25 and a washer 26 to supportmember 19 directly over a cross-shaped depression 27 in support member19. The crossshaped depression 27 in support member 19 is suitablyproportioned and dimensioned to receive and contain block 22 withineither of its perpendicularly related arms.

U-shaped bar 23 is fixedly attached at the ends of its legs 23A and 238in aligned holes 35A and 358 in block 22 and perpendicularly securedthereto by means of screws 28A and 288 as shown.

The mounting of block 22 to support member 19 entails the insertion ofpivot pin 24 through washer 26, spring 25, center hole 29 of block 22and center hole 31 in depression 27 formed in member 19. Pivot pin 24 isthen secured to support member 19 by means of a screw or spreading rivet32 applied from the opposite side of support member 19 within whichdepression 27 is formed.

Block 22 may be aligned within either of the two perpendicular arms ofdepression 27 by the user grabbing a hold of the u-shaped bar 23 andpulling it away from the support member 19 against the bias of spring 25and then upon being released after proper rotation and relativepositioning it will fall into one of the arms of depression 27 throughthe action of spring 25.

Coupler 21 has a generally cylindrical shape modified at one end by theremoval of a semi-cylindrical section to provide a flat surface 33.Surface 33 passes longitudinally through the approximate center of thecylindrical outline of coupler 21. A hole 34 perpendicularly arranged topass through surface 33 at one end of the coupler 11 is dimensioned toreceive leg 23B of ushaped bar 23 in a pivotal relationship.

In the assembly of u-shaped bar 23 to block 22 its leg 23B is firstpassed through hole 34 of coupler 21. Legs 23A and 23B of the u-shapedbar are then passed, respectively, through holes 35A and 35B in block22, holes 35A and 358 being aligned along a longitudinal centerline ofblock 22. The surface 33 of coupler 21 now rests adjacent the surface ofblock 22 and is retained in that position by an annular shoulder on leg23B adjacent the opposite end of hole 34.

Rod 18 supporting spike 16 at its lower end is attached at its upper endwithin an aperture arranged along the longitudinal axis of coupler 21for receiving and retaining rod 18. spike 16 is attached by means ofthreads 36 to the lower end of rod 18, the length of rod 18 beingappropriately dimensioned to allow spike 16 to penetrate center hole 17in tread at the base of crutch 10.

As shown in FIG. 1, when block 22 is vertically oriented and rests inthe vertical arm of depression 27 of support member 19, leg 23B of bar23 is in its lowermost position and hence spike 16 coupled to leg 23B isconsequently in its lowermost position. In this position tip 36 of spike16 is exposed below the bottom surface 37 of tread 15. By virtue of theaction of spring 25 in forcing block 22 to remain rigidly secured withinthe vertical arms of depression 27, spike 16 is rigidly held in thisextended position wherein it serves reliably as a skid-proof tread atthe base of crutch for use in preventing slippage of crutch 20 on icy orslippery surfaces.

When the user of the crutch has cleared the slippery areas and wishes topass over the non-slippery surfaces which might be damaged or marred byspike 16, he merely grasps u-shaped bar 23, pulls it outwardly from thecrutch support member 19 to withdraw block 22 from depression 27 formedtherein. He then rotates block 22 about pivot pin 24 through an angle of90 degrees and then releases it to allow spring to move block 22 intothe horizontal arm of depression 27, as shown in FIG. 4. Leg 23B of theu-shaped bar 23 is now moved to a relatively higher position carryingcoupler 21, rod 18 and spike 16 upward with support member 11 and 12 ofthe crutch sufficiently to cause spike 16 to be withdrawn inside hole 17so that tip 36 no longer extends below surface 37 at the base of tread15. The flexible hard rubber body of tread 15 now serves as anappropriate bearing surface for the crutch.

As shown in FIGS. 1 and 3, tread 15 is formed in a manner which permitsits easy replacement if it becomes excessively worn. In addition to itscenter hole 17 which receives and horizontally positions spike 16, twodead holes 38 and 39 may be provided one on either side of hole 17.These are arranged to receive the bases of vertical support members 11and 12 of crutch 10. The dimensions of holes 38 and 39 are appropriateto produce a force fit with member 11 and 12.

A second embodiment of the invention as shown in FIGS. 6-9 utilizes aretracting mechanism 41 comprising a modified supporting member 42 andcam-shaped block 43.

Supporting member 42 is fashioned from flat stock which is mounted as aweb spanning vertical supports 11 and 12 just below hand grip 14 as didmember 19 of the first embodiment. In place of the cross-shapeddepression 27 in support member 19 of the first embodiment, supportingmember 42 has a depression 44 which is semicircular in shape and opensat its lower edge as shown in FIG. 9.

Cam-shaped block 43 is cut from a piece of fiat stock of a thicknessnearly equal to the depth of depression 44 in the shape of a circlesupplemented by a ninety degree sector of a second, slightly largercircle. The ninety degree sector forms a shoulder or protrusion 45forming a first radially extending shoulder 45A and a second radiallyextending shoulder 45B.

Cam-shaped block 43 is pivotally mounted to member 42 by means of apivot pin 46 passing through a center hole 47 in block 43 and a centerhole 48 in supporting member 42. The smaller circle of block 43 fitsrotatably inside semi-circular depression 44 of supporting member 42 asshown in FIGS. 6, 7 and 8.

The cam-shaped block 43 is rotatable about pivot pin 46 withindepression 44 and when rotated in a counter clockwise direction isstopped when shoulder 45A comes into contact with a bumper surface 49Alocated on the under side of supporting member 42 just to the right ofdepression 44. Its clockwise rotation is stopped when its shoulder 45Bcomes into contact with bumper surface 49B located on the under side ofsupporting member 42 just to the left of depression 44.

Spike 16 is supported by rod 18 coupled to the shifting mechanism 41 bymeans of the coupler 21, in the manner described for FIGS. l-5, withcoupler 21 being pivotally attached to the shifting mechanism 41 bypivot pin 51 passing through hole 34 of coupler 21 and hole 52 locatednear the edge of protrusion 45 and shoulder 453 as shown in FIG. 9.

It will now be observed that by virtue of the location of hole 52 nearshoulder 45B rather than at the center of protrusion 45, pivot pin 51 isin a relatively higher position when block 43 is rotated fully clockwiseand in a relatively lower position when block 43 is rotated fullycounterclockwise when the crutch is in a vertical position relative tothe ground. Rod 18 is appropriately dimensioned to provide for theprotrusion of spike 16 under the fully counter clockwise condition ofFIG. 7 and to provide for retraction of spike 16 under the fullyclockwise condition of FIG. 6.

To provide for mechanical stability of block 43 in either the clockwiseor counter clockwise positions, a tension spring 53 is attached at oneend to a ring 54 extending from the head of pivot pin 51 and at theother end to a ring 55 secured to member 42. The position of ring 55 ischosen to cause the line of force produced by spring 53 to lie above pin46 when block 43 is rotated clockwise thereby sustaining block 43 in itsclockwise position. Similarly, when block 43 is rotatedcounterclockwise, the line of force of spring 53 lies to the right ofpin 46 where it is sustained in that counterclockwise position.

The retracting mechanism may be easily and conveniently shifted from oneposition to the other to retract or expose spike 16 by appropriatelyrotating camshaped block 43 to either of the two stable conditionsagainst the initially restraining action of spring 53.

An improved crutch has thus been provided which is easily converted in amatter of seconds for use on slippery or on normal dry surfaces. Twonovel and practical retracting mechanisms have been provided as meansfor exposing or retracting the spike at the base of the crutch. Othervariations in design will be obvious such as the incorporation of theretracting mechanism into the hand grip as an integral part thereof.

In accordance with good manufacturing practice, the structural membersof the disclosed crutch may be formed of metal, plastic or wood with thetread member formed of a resilient material such as, for example, rubberor suitable plastic either smooth or formed with ridges or othersuitable gripping surfaces.

Although but two embodiments of the invention have been illustrated anddescribed, it will be apparent to those skilled in the art that variouschanges and modifications may be made therein without departing from thespirit of the invention or from the scope of the appended claims.

What is claimed is:

l. A crutch convertible for use on dry or slippery surfaces comprising:

a pair of spacedly arranged elongated support members interconnected atone end by a cross member for fitting under the arm pits of a user,

a handgrip arranged to extend laterally between said support members ata point between their ends,

a tread member formed of resilient material for gripping a smoothsurface interconnecting said support members at their other groundengaging ends,

said tread member having an aperture extending therethroughlongitudinally of said crutch,

a rod arranged between and within the plane of said support memberslongitudinally of said crutch with one end movable in said aperture ofsaid tread member,

a spike removably attached to said one end of said rod for aiding ingripping a slippery surface,

the other end of said rod extending adjacent to said handgrip,

means mounted adjacent said handgrip and attached to said other end ofsaid rod for moving said rod within said aperture of said tread memberto protrude said one end of said rod beyond said tread member or retractit within said aperture,

said means comprising a locking means for holding said rod in itsretracted and extended positions,

said locking means comprises a supporting plate having a slotted crosslike configuration with one arm of the slot extending longitudinally ofthe crutch and the other arm laterally thereof,

a flat plate pivotally mounted at said one end of said rod for fittinginto either arm of said slotted configuration, and

means for moving said plate into either arm of said slotted likeconfiguration to lock said rod in either the retracted or protrudingposition.

1. A crutch convertible for use on dry or slippery surfaces comprising:a pair of spacedly arranged elongated support members interconnected atone end by a cross member for fitting under the arm pits of a user, ahandgrip arranged to extend laterally between said support members at apoint between their ends, a tread member formed of resilient materialfor gripping a smooth surface interconnecting said support members attheir other ground engaging ends, said tread member having an apertureextending therethrough longitudinally of said crutch, a rod arrangedbetween and within the plane of said support members longitudinally ofsaid crutch with one end movable in said aperture of said tread member,a spike removably attached to said one end of said rod for aiding ingripping a slippery surface, the other end of said rod extendingadjacent to said handgrip, means mounted adjacent said handgrip andattached to said other end of said rod for moving said rod within saidaperture of said tread member to protrude said one end of said rodbeyonD said tread member or retract it within said aperture, said meanscomprising a locking means for holding said rod in its retracted andextended positions, said locking means comprises a supporting platehaving a slotted cross like configuration with one arm of the slotextending longitudinally of the crutch and the other arm laterallythereof, a flat plate pivotally mounted at said one end of said rod forfitting into either arm of said slotted configuration, and means formoving said plate into either arm of said slotted like configuration tolock said rod in either the retracted or protruding position.